Weedy red rice has novel resistance resources to biotic stress

Authors: Jia, Yulin; Gealy, David

Submitted to: The Crop Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2018
Publication Date: 7/27/2018
Citation: Jia, Y., Gealy, D.R. 2018. Weedy red rice has novel resistance resources to biotic stress. The Crop Journal. https://doi.org/10.1016/j.cj.2018.07.001.
DOI: https://doi.org/10.1016/j.cj.2018.07.001

Interpretive Summary: Weedy red rice (WRR) is an aggressive weed of cultivated rice and can also naturally interbreed with this crop. As a result, WRR populations have maintained high genetic diversity and can be a source of novel genetic diversity for biotic stress tolerance. In this review, we explore genetic and physiological merits of WRR that can be beneficial for preventing devastating rice blast and sheath blight diseases. Novel resistance genes to blast and sheath blight have been recently identified in the two main biotypes of WRR in the US (those with black-colored hulls and those with straw-colored hulls) and can be used as new sources of disease resistance for breeding. Twenty-eight accessions of WRR from the southern USA were characterized and placed in the National Small Grains Collection, and are available for identification of novel genetic factors to prevent biotic stress.

Technical Abstract: Weedy red rice (Oryza sativa; WRR), a close relative of cultivated rice, is a highly competitive weed that commonly infests rice fields and can also naturally interbreed with rice. Useful genes for biotic stress have been maintained in WRR and can be explored for breeding. Here we demonstrate that genetic and physiological merits of WRR can be beneficial in preventing major rice diseases. Rice blast, caused by the hemibiotrophic fungal pathogen Magnaporthe oryzae, and sheath blight disease, caused by the necrotrophic pathogen Rhizoctonia solani, are the two most damaging biotic stresses of rice. Many major and minor resistance genes/QTL have been identified in cultivated and wild rice relatives. However, novel QTL were recently found in the two major US biotypes of WRR, blackhull-awned (BH) and strawhull-awnless (SH), suggesting that WRR has evolved novel genetic mechanisms to cope with these biotic stresses. Twenty-eight accessions of WRR (PI 653412 - PI 653439) from the southern USA were characterized and placed in the National Small Grains Collection, and are available for identification of novel genetic factors to prevent biotic stress.